PHP application JSON skills explained_PHP tutorial

php json_decode return data js processing

After php json_decode, the data returned to the front desk is such as: encode_str =》{"green":10,"size":5," strock":12}
Then js can instantiate json data into an object through eval("obj = " + encode_str + ";");
, and you can get the data directly through obj.green.

In Javascript, {} can be used to represent an object, and [] can be used to represent an array, such as:

var obj={"a":"v","b":"x"};//This means that variable obj is an object, which has two attributes: a and b, and the attribute values ​​are: v and x.
var arr=["v","x"];//This means that the variable arr is an array, which has two elements, the indexes are 0 and 1, and the values ​​are: v and x.
JSON is actually a format in which these two formats are mixed together to represent the logical structure of data. In fact, JSON is a mixture of objects and arrays in Javascript

PHP provides special functions to generate and parse data in JSON format. The data parsed by PHP has the same meaning as the original Javascript data, that is, Javascript objects are parsed into PHP objects, Javascript arrays are parsed into PHP arrays, and PHP applies JSON The function of PHP parsing JSON is: json_encode($PHPcode);
The function of PHP parsing JSON is: json_decode($JSONcode);

So there are many forms of JSON, and different forms have different forms after being interpreted by PHP.

Copy code The code is as follows:

//Form 1: It is completely in the form of an object. This form of data is in Javascript
is also called a related array. Different from ordinary arrays,
can be accessed through string indexing (use "[]" or "."
to represent levels)
$json ='{"item1":{"item11":{"n":"chenling",
"m":"llll"},"sex":"male","age":"25"}, "item2":
{"item21":"ling","sex":"女","age":"24"}}';
$J=json_decode($json);
print_r($J);

will output:

Copy the code The code is as follows:

stdclass Object m] => llll
)
[sex] => Male
[age] => 25
)
[item2] => stdClass Object
(
[item21] => ling
[sex] => female
[age] => 24
)
)


For example, I want After obtaining the attribute whose value is chenling, you should access it like this:
$J->item1->item11->n;//This will get the value of attribute n: chenling
In fact, this kind of access The form is similar to accessing ordinary object properties, and is equivalent to accessing a 3-dimensional array.

Copy code

The code is as follows:

//Form 2: Mixing objects and arrays $json='{" item1":[{"name":[{"chen":"chenling","ling":"chenli"}],"sex":"Male","age":"25" },{"name":"sun","sex":"female","age":"24"}]}';

$J=json_decode($json);

print_r ($J);
will output:
stdClass Object
(
[item1] => Array
(
[0] => stdClass Object
(
[name] => Array
(
[0] => stdClass Object >)
)
[sex] => Male
[age] => 25
)
[1] => stdClass Object
(
[name ] => sun
[sex] => female
[age] => 24
)
)
)


For example, I want To get the element whose value is chenling, you should access it like this:
$J->item1[0]->name[0]->chen;//This will get the value of the element chen: chenling
In fact, the JSON form of this PHP application combines the access methods of objects and arrays, which is equivalent to accessing a 5-dimensional array.



Copy code

The code is as follows:

//Form 3: Complete array form
$json='[["item1","item11"],[
"n","chenling"],["m", "llll"]]';
$J=json_decode($json);
print_r($J);
will output:
Array
(
[0] => ; Array
(
[0] => item1
[1] => item11
)
[1] => => n
[1] => chenling
)
[2] => Array
(
[0] => m ; llll
)
)


For example, if I want to get the element whose value is chenling, I should access it like this:

$J[0][1];//This will get the element whose element value is chenling
But there is a disadvantage in using this method, that is, you cannot use strings as indexes. You can only use numbers. This problem can be solved in the form of complete objects. In fact, this access method is the access method of an array, which is equivalent to accessing an array. 2D array.

PHP application JSON summary:

From the above PHP application JSON example, we can see that JSON is somewhat similar to XML. It can also transfer structured data between PHP and Javascript, which is very convenient to use.

It should be noted that each attribute and attribute value are enclosed by quotation marks "".

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